With everyone so concerned about Arizona's new immigration law, I'm surprised no one's talked about how we actually got our border with Mexico. Before 1843, the southern part of Arizona and New Mexico was a part of Mexico. James Gadsden was instructed by the president to buy up a huge portion of Mexico, but our neighbor to the south balked. As a consolation prize Mexico did agree to sell us a small sliver, which we now call the Gadsden Purchase. Without that deal, Tucson would be in Mexico today. Of course Arizona wasn't a state back then--in the days before air conditioning, the population was small. When Arizona was considered for statehood, many proposed combining what is now Arizona with New Mexico to create a super-sized state called Montezuma. For a bigger map, go here.